change microswitch to a light barrier

ICY_SNAKE

Hello,

i am new here.
My printer is a modix 60 V3.
There is a DUET board installed.
The modix Printer does not have Z-Stop switch.
(so without it could destroy my hotend)
I like to add a light barrier. (also like to replace the microswitches for X&Y)
Does anyone already have it? Any info installing a light barrier instead of a microswitch?

Thx for your help
Dieter

T3P3Tony

@icy_snake you an use pretty much anything that can switch a 3.3V IOn.in from 0 to 3.3V or from 3.3V to 0V to act as a "switch" in this case. So a simple microswitch is used to connect an IOn.in to ground as an endstop. So the question is what options for outputs do the light barriers you are looking at have. Also how would you integrate them into the mechanics of the printer?

mrehorstdmd

I put opto endstops in all three axes in my printer and ran tests of the precision- they came out excellent.

Blog posts here:
https://drmrehorst.blogspot.com/2020/01/ummd-gets-opto-endstops.html
https://drmrehorst.blogspot.com/2020/03/testing-ummds-xy-optical-endstops.html
https://drmrehorst.blogspot.com/2020/03/a-new-z-axis-optical-endstop-design-for.html
https://drmrehorst.blogspot.com/2020/03/testing-ummds-new-z-axis-optical.html

o_lampe

@icy_snake Beam brakers (light barrier = Lichtschranke in German) are easy to use. You have to supply 3.3 or 5V, which is the only difference to some microswitches. The signal is often inverted, so you have to check endstops with M119 and perhaps use M574 X? S? P"!xstop" etc. (the ! inverts the signal)

T3P3Tony

@ICY_SNAKE I has a light curtain in mind as opposed to an opto switch. If you mean a opto switch then as has already been said there are used frequently.

If you mean a light curtain across the whole bed - thats a different story!

ICY_SNAKE

@t3p3tony Hello Tony,
i will print some brackets to hold the pcb with the beam braker.

Thats what I would use.
https://www.amazon.com/gp/product/B07JMDLD84/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

dc42

@icy_snake see https://duet3d.dozuki.com/Wiki/Connecting_endstop_switches#Section_3_3V_compatible_optical_endstop.

T3P3Tony

@icy_snake ahh ok yes, just a confusion in terminology - these are optical endstops as we call them. dc42 linked to the documentaiton for them.

mrehorstdmd

@icy_snake I show those opto endstops as currently unavailable, but there are other suppliers who make the same thing. Look for the LM393 comparator chip on whatever devices you use. That chip switches the output between logic 0 and 1 very quickly and I think that is responsible for the high precision of the endstops.

This one uses the LM393 comparator